Folding scaffold for construction work

Abstract: In a scaffold for construction work, four supports (1a,1b) are provided at the respective corners of a rectangle. The front and rear supports on each side are connected to each other by a connecting frame (11) which can be folded without changing its height. After the connecting frames are folded, a scaffolding floor member (6b) provided on the top surface enclosed by the four supports can be lowered by rotating it about one of its ends.

Description: The present invention relates to a folding scaffold for construction work which allows operators to climb to high places, e.g. when they wish to work on a ceiling or a high part of a wall at a construction site, and which can be moved easily. Conventionally, when construction work has to be performed on a ceiling or a high part of a wall, a scaffolding frame is built parallel with the wall using pipes and clamps, and scaffolding plates are mounted on the frame so that operators can stand thereon. A folding scaffold is also known, which can be easily carried and assembled. In such a folding scaffold, as disclosed in Japanese Patent Application Unexamined Publication No. Hei. 2-85467 and Japanese Utility Model Application Unexamined Publication No. Sho. 62-110439, wheels are attached to the lower ends of supports to make the scaffold mobile. Furthermore, the scaffold is divided along its centre line into two halves which are connected by hinges. To fold the scaffold, the centre-side ends of the scaffolding plates of the two halves are lifted and the halves are vertically erected at the centre of the scaffold. The scaffold is stored in this state. Since such a folding scaffold is folded by erecting the halves vertically, it has a large height when in the storage condition. As a result it is inconvenient to transport; for example, it cannot be loaded into a freight elevator. Furthermore, since the scaffold has a large height when folded, it is difficult for a single operator to fold the scaffold vertically and unfold it horizontally. GB-A-1311569 discloses a folding scaffold comprising supports arranged at at least the four corners of a rectangle and having respective wheels at their lower ends, horizontal bars connecting the two front supports and the two rear supports respectively, a first connecting frame extending between the front and rear supports and located substantially in the upper half space of the scaffold and a second connecting frame extending between the front and rear supports and located substantially in the lower half space of the scaffold, each connecting frame having front and rear parts rotatably connected to the respective supports about vertical axes and being divided centrally into two adjacent halves that are hingedly connected to each other about vertical axes, and a scaffolding floor member provided at the top of the scaffold, substantially within the area bounded by the four said supports and of a size large enough to substantially cover the scaffold top. The present invention is characterised in that the said first connecting frame extends between the front and rear supports on one side of the scaffold and the said second connecting frame extends between the front and rear supports on the other side, whereby, to fold the scaffold, the said connecting frames on both sides are foldable inwardly about their vertical axes. In one form of the invention the said floor member has its front or rear end rotatably connected to the top regions of the adjacent supports about a horizontal axis and engagement members are provided at the other end of the floor member for detachable engagement with the tops of the other supports, whereby, to fold the scaffold, the said floor member is hingeable downwardly about its horizontal axis. To fold a scaffold as in this form of the invention, the engagement members of the scaffolding floor member are released from their connection with the supports and slightly lifted, and the connecting frames on both sides are then folded about the respective vertical axes so that their central portions move inwardly until the frames are folded adjacent to each other between the two supports. Then the floor member is folded down about its horizontal axis. In this matter, the scaffold can be stored with its height the same as before folding and furthermore it can be moved easily on its wheels. To erect such a folding scaffold from its storage condition, the scaffolding floor member is first rotated upwardly about its horizontal axis. Then the folded connecting frames on both sides are extended and the engagement members on the floor member are engaged with the respective supports. In another form of the invention the said floor member comprises a scaffolding plate laid on the said horizontal bars connecting the front supports and the rear supports. Each said support preferably comprises two telescopic pipes capable of expansion and contraction lengthwise, fixing means being provided to fix the supports at a desired length. Furthermore, handrails may be detachably mounted on the top surface of the scaffolding floor member. To change the height of the scaffold, the length of each support, when of telescopic double-pipe structure, is adjusted after releasing the fixing means thereof. To ensure the safety of operations to be performed on the scaffold, the aforementioned handrails are preferably attached to the periphery of the top surface of the scaffolding floor member. The handrails are removed when the scaffold is folded. Another form of the invention comprises two scaffolds as set forth above connected together end to end, the said front supports of the respective scaffolds being interconnected to form a central supporting member. Such a scaffold may be converted to the storage condition in a similar manner to that described above. That is, the floor members on both sides are lowered about their horizontal axes after the connecting frames on both sides of the central supporting members have been folded in. This type of scaffold is restored to its state of use in a similar manner. That is, the floor members on both sides are raised to the horizontal, the connecting frames on both sides are extended, and finally the engagement members of the respective floor members are engaged with the tops of the outer supports. Some embodiments of the invention will now be described by way of example and with reference to the accompanying drawings, which:- Figure 1 is a side view of a scaffold for construction work according to a first embodiment of the present invention; Figure 2 is a front view of the scaffold of Figure 1; Figure 3 is an explanatory side view showing the scaffold in its folded condition; Figure 4 is an explanatory top view showing the scaffold in its folded condition; Figure 5 is a side view of a scaffold for construction work according to a second embodiment of the invention; Figure 6 is a side view of a scaffold for construction work according to a third embodiment of the invention; and Figure 7 is a front view of the scaffold of Figure 6. The folded scaffold of Figures 1-4 includes supports 1a and 1b which are provided at positions corresponding to the four corners of a rectangle. Having a double-pipe structure, each support 1a or 1b is capable of telescopic expansion and contraction. The outer pipe has a pin hole 2a at its bottom end, and the inner pipe has pin holes 2b at suitable intervals in the longitudinal direction. When the double pipes constituting the supports 1a and 1b have been adjusted to a desired length, the length can be fixed by a fixing means in the form of a pin 3 which is inserted through the pin holes 2a and 2b. Furthermore, a wheel 5 is attached to the bottom end of each supporting pipe 1a or 1b through a swivel shaft 4 so that the scaffold can easily be moved in any direction. The two front supports 1a are connected to each other by a number of horizontal bars 5b, and the two rear supports 1b are interconnected in the same fashion. The horizontal bars 5b serve as a ladder for an operator to climb up in order to stand on the scaffolding floor members 6a and 6b (described later). While the outer pipes of the supports are connected to each other by the horizontal bars 5b as just mentioned, the lower ends of the inner pipes are connected to each other by respective horizontal bars 5a. A narrow scaffolding floor member 6a is fixed to the two front supports 1a. The outside region of the scaffolding floor member 6a is connected to the front supports 1a by stays 7 so as to increase the strength of the horizontal support for the floor member. The top area enclosed by the four supports 1a and 1b, except for the area of the narrow scaffolding floor member 6a, is covered with a wide scaffolding floor member 6b. Stays 7a are attached to the front end of the scaffolding floor member 6b, which stays are connected to the narrow scaffolding floor member 6a through horizontal shafts 8 so that the wide scaffolding floor member 6b can rotate about the shafts 8 to lower its rear end. Each of the scaffolding floor members 6a and 6b is constructed from punched metal or steel plates mounted on a grid-like frame, to allow operators to stand thereon. The edges of the scaffolding floor members 6a and 6b which correspond to the periphery of the scaffold top surface, have engagement holes 15 for insertion of handrails to prevent workers from falling off the scaffold. The lower ends of handrails 16 are inserted into the engagement holes 15 when the scaffold is in use, and are removed when the scaffold is to be folded. Spigots 9 project from both sides of the rear end of the wide scaffolding floor member 6b, and the upper end portions of the two rear supports 1b have engagement holes 10 for receiving the spigots 9. When the scaffold is in use, the spigots 9 are inserted in the engagement holes 10 and the connecting frames (described below) are held extended. When the scaffold is to be folded, the spigots 9 are removed from the holes 10. Connecting frames 11 are provided between the respective pairs of front and rear supports 1a and 1b. Each connecting frame 11 has a height approximately half that of the said supports, and the connecting frame on one side is located in the upper half space of the scaffold while the connecting frame on the other side is located in the lower half space, so that the frames do not interfere with each other when the scaffold is folded in the manner to be described below. The upper and lower ends of the front and rear ends of each connecting frame 11 are rotatably connected, through vertical spigot shafts 13, to brackets 12 attached to the respective supports 1a and 1b. Each connecting frame 11 is sub-divided along its vertical centre line, and the resulting halves are rotatably connected to each other through vertical shafts 14 on the dividing line. As shown in Figure 4, when the scaffold is folded, each connecting frame 11 is hinged at its centre, with its centre portion moving inward, so as to assume a V shape. Finally the connecting frames 11 are folded adjacent to each other between the two front supports 1a. After the connecting frames have been folded, the wide scaffolding floor member 6b is rotated about its connecting shafts 8 to lower its rear end. Thus, as shown in Figure 3, the scaffold is foldable into its storage condition without any change in its height. The pairs of front and rear supports 1a and 1b are each provided with a metal locking member 17 and a catch 18, respectively. By engaging the locking members 17 with the catches 18 after the scaffold has been folded to the storage condition (see Figure 3), the folded scaffold is prevented from opening. Furthermore, to prevent the connecting frames 11 from hinging outwards (rather than inwards) when folded, suitable stoppers (not shown) are provided in the vicinity of the mountings at the front and rear ends of the connecting frames. While, in this embodiment, both a narrow scaffolding floor member 6a and a wide scaffolding floor member 6b are provided, the wide floor member may be used without the narrow floor member, if desired. In this case, in the same manner as in the above described embodiment, connecting members may be attached to the top portions of the supports located at the front or rear end of the single scaffolding floor member 6b, and the floor member rotatably connected to the connecting members through horizontal shafts 8. A folding scaffold according to a second embodiment of the invention will be described with reference to Figure 5. In the second embodiment, two scaffolds according to the first embodiment are connected together such that a total of four supports located at the central region are combined to produce two central supporting members. Thus two supports 21 are connected to each other and a wheel 22 is attached to the bottom of the connected structure, to constitute a central supporting member 23. The two central supporting members 23 thus formed are disposed with a certain interval between them. Connecting frames 11, each formed in two halves hingedly connected to each other so as to be foldable, are provided on both sides of each central supporting member 23. Having the same configuration as in the first embodiment, the connecting frames 11 can be folded as shown in Figure 4 to positions adjacent to each other and between the central support members 23. An outer supporting pipe 1b, as in the first embodiment, having a wheel 5 attached to its lower end, is provided at the outer end of each connecting frame 11. Scaffolding floor members 24 located on each side of the central supporting members 23 are connected at their inner ends to connecting members 25 through horizontal shafts 8 so that each floor member can be rotated about its shaft 8 between horizontal and vertical positions. Furthermore, as in the first embodiment, spigots 9 are provided on the outside ends of the scaffolding floor member 24, to engage in holes 10 in the tops of the supports 1b. Thus, after the respective connecting frames 11 have been folded adjacent to each other between the central supporting members 23, both of the floor members 24 can be rotated about their shafts 8, to lower their outer ends, thereby placing the scaffold in its storage condition. If desired, the scaffolding floor member 24 may comprise two floor members, i.e. respective wide and narrow members 6a and 6b as in the first embodiment, or a single floor member 6b. The lengths of the supports 1b and supporting members 23 are adjustable as in the first embodiment. A third embodiment of the invention is shown in Figures 6 and 7. In this embodiment, no scaffolding floor members are used to cover the top surface enclosed by the four corner supports 1a and 1b. Instead, a scaffolding plate 25 is hung between two horizontal bars 5b attached to the upper ends of the front supports 1a and the rear supports 1b respectively, to form a scaffolding floor. Hooks 26 attached to the front and rear ends of the scaffolding plate 25 are hooked over the top horizontal bars 5b. Further, engagement holes 27 are provided in the respective upper ends of the four supports 1a and 1b to receive the lower ends of handrails 16. Otherwise this embodiment is the same as the first embodiment. It is possible to connect two scaffolds according to the embodiment of Figures 6 and 7 in the same manner as in the second embodiment of Figure 5. It will thus be seen that, in the described embodiments of the invention, a scaffold is constituted such that when it is folded, the connecting frames thereof are folded adjacent to each other between two front supports without any change in height, and a wide scaffolding floor member is rotated about its horizontal mounting shafts so as to lower its outer end. As a result, the height of the scaffold can be kept low in its storage state and the scaffold can be moved easily. Furthermore, when the scaffold thus folded is extended for use, only the following simple operation has to be performed: the wide scaffolding floor member is rotated about its mounting shaft so as to extend horizontally, then the connecting frames are unfolded, and finally the engaging spigots are inserted into their receiving holes in the upper ends of the supports. Thus, the operation of extending the folded scaffold can be performed easily. Furthermore, when no scaffolding floor member is used and a scaffolding plate is hung between front and rear horizontal bars, the scaffold can again be folded easily from its state of use without any change of its height, in a manner similar to the above. Since the length of the supports is adjustable, the scaffold can be used for different heights of construction work. Handrails can be attached to the top of the scaffold to ensure workers' safety. Furthermore, where scaffolding floor members and connecting frames are provided on both sides of central supporting members, a foldable scaffold having a large floor area can be provided.

Claims: A folding scaffold comprising supports (1a,1b) arranged at at least the four corners of a rectangle and having respective wheels (5) at their lower ends, horizontal bars (5b) connecting the two front supports (la) and the two rear supports (1b) respectively, a first connecting frame (11) extending between the front and rear supports and located substantially in the upper half space of the scaffold and a second connecting frame (11) extending between the front and rear supports and located substantially in the lower half space of the scaffold, each connecting frame having front and rear parts rotatably connected to the respective supports about vertical axes (12) and being divided centrally into two adjacent halves that are hingedly connected to each other about vertical axes (14), and a scaffolding floor member (6b) provided at the top of the scaffold, substantially within the area bounded by the four said supports and of a size large enough to substantially cover the scaffold top, characterised in that the said first connecting frame extends between the front and rear supports on one side of the scaffold and the said second connecting frame extends between the front and rear supports on the other side, whereby, to fold the scaffold, the said connecting frames on both sides are foldable inwardly about their vertical axes. A scaffold according to claim 1, wherein the said floor member (6b) has its front or rear end rotatably connected to the top regions of the adjacent supports about a horizontal axis, and engagement members are provided at the other end of the floor member for detachable engagement with the tops of the other supports, whereby, to fold the scaffold, the said floor member is hingeable downwardly about its horizontal axis. A scaffold according to claim 1, wherein the said floor member comprises a scaffolding plate (25) laid on the said horizontal bars (5b) connecting the front supports (1a) and the rear supports (1b). A scaffold according to any of claims 1 to 3, wherein each said support (1a,1b) comprises two telescopic pipes capable of expansion and contraction lengthwise. A scaffold according to any preceding claim, further comprising handrails (16) detachably mountable on a top surface of the said floor member (6b). A scaffold comprising two scaffolds according to any of claims 1 to 5 connected together end to end, the said front supports (21) of the respective scaffolds being interconnected to form a central supporting member (23).

Inventors: YONAHARA YOSHIHIRO, YONAHARA, YOSHIHIRO
Applicants: JAPAN STEELS INTERNATIONAL INC, JAPAN STEELS INTERNATIONAL INC.
Application year: 1994
Main classification: E04G1
IPC codes: E04G1